national~iversity · 2019. 11. 21. · previous work on methods of calculating higher order...
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80/1972
THE AUSTRALIAN NATIONAL~IVERSITY FACULTY OF SCIENCE
DEPARTMENT OF THEORETICAL PHYSICS
ANNUAL REPORT 1971
Introduction:
Training at both undergraduate and postgraduate level is provided
for students intending to become theoretical physicists. The under
graduate course also provides a background in theoretical physics for
other students.
This year a University Medal, and the Shell Company Prize in
Science were awarded to students in the department.
Research has been carried out in the fields of plasma physics,
astrophysics, optical aberration theory, nuclear physics, general
relativity theory and cosmology.
Teaching:
Student enrolments and examinations are set out in the attached
table.
Work of Graduate Students ~
W. Sy continued his work on problems involving non-linear inter
actions in a magneto-active plasma. Two papers were prepared jointly
with Dr. Melrose. To date one of these has been published.
A. O'Leary continued with his investigations of the properties
and design of zoom systems.
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Research:
H.A. Buchdahl
In the context of cosmological theory one requires to know the
equations of arbitrary time-like geodesics. In fact, all geodesics of
a Riemann space may be subsumed under a single two-point function:
Synge's world function, or the characteristic function equivalent to
it. The form of this characteristic function for an arbitrary
Robert0on-Walker space was obtained explicitly. A paper has been
accepted for publication in General Relativity and Gravitation.
The classification, due to Schouten, of tensors and tensor den
sities is unsatisfactory in as far as it does not cover all possible
tensorial objects which may be constructed from those . included in his
classification. A new terminology has been developed, and published
in TENSOR.
In response to an invitation from the Tensor Society of Japan to
contribute to a special volume in honour of Kawaguchi's 70th birthday,
certain problems associated with the Dirac algebra, formulated in
terms of a generally covariant calculus of four-spinors, were
investigated. An appropriate manuscript has been submitted.
It was shown that, given any static vacuum solution of Einstein's
equations, a corresponding static vacuum solution of the field
equations of the so called scalar-tensor theory can be written down by
inspection. A manuscript has been submitted.
Previous work on methods of calculating higher order aberration
coefficients of symmetric optical systems which had covered the fifth
and seventh order coefficients only was consolidated and explicitly
extended to the ninth order. An extensive manuscript has been
submitted.
As a counterpart to the work just described an investigation was
begun of the theory of aberration coefficients of systems without any
symmetries at all. Two manuscripts were submitted.
Jointly with Dr. Sands the theory of reversible semi-symmetric
systems was reconsidered. A manuscript has been accepted for
publication in Optik.
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The generic theory of aberrations of systems which are invariant
under finite, but not continuous, rotations about a line has been
investigated. A manuscript has been submitted.
A good deal of other research work which has not yet led to the
submission of manuscripts has not been described.
R.T. Cahill
The three body scattering problem in nuclear physics was further
investigated with emphasis on the complicated unitarity constraints
which arise in this problem. Work on a quasi-unitary approximation,
begun while at the University of New South Wales, has shown that this
approximation may be interpreted as incorporating the effect, which
was shown to be large, of the initial-state interaction process in
break-up reactions. This work was submitted for publication as "The
n-d initial-state interaction in n-d break-u~', with Dr. Sloan as
co-author. Further work on the unitarity constraints led to the
development of an exact unitary model which involves tractable on
energy-shell integral equations. A paper entitled "A unitary model
for three body collisions" was submitted for publication. Following a
seminar given at Flinders University, one of Professor McCarthy's Ph.D.
students undertook a detailed numerical investigation of this model.
His results have shown that the processes accounted for in this three
body collision model are those substantially responsible for the
observed properties of the experimental results.
Theoretical work in collaboration with groups of experimentalists,
substantially done at the end of 1970, has led to the publication of
one paper and the submission for publication of two other papers, all
concerning triple correlation experiments on n-d break-up .
Experimental groups at California and Grenoble were involved.
D.B. Melrose
The theory of synchrotron radiation was extended to include the
effects of synchrotron reabsorption, of the emission from particles
with small pitch angles and at low frequencies, and of the transfer of
the radiation through an inhomogeneous source on the degree of
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circular polarization . One paper was published in Astrophysics and
Space Science and two in Astrophysical Letters on this subject.
The classical counterpart to Compton scattering was investigated
in detail. Two papers were published in Astrophysics and Space
Science on this topic . Further extension of the theory to include
induced scattering, double Compton scattering and the effect of a
background magnetic field, the last topic in collaboration with W. Sy
[Ph . D. student], were considered . Papers on the first two topics have
been accepted for publication and a paper on the third topic (with
W. Sy) has been submitted for publication.
An investigation of possible theories for type I solar radio
bursts was carried out , The results of this investigation have been
incorporated into an unpublished technical report. Non-linear
processes in a plasma were studied in this connection . A manuscript
on the symmetry properties of tensors describing the non-linear
responses has been prepared.
Three papers presented at conferences have been published . One
was concerned with the acceleration of ultrarelativistic papers in the
Crab nebula (International Astronomical Union Symposium on the Crab
Nebula), the second was concerned with the scattering of cosmic rays
(Twelfth International Conference on Cosmic Rays), and the third,
which was in collaboration with W. Sy, was concerned with the line
splitting in solar radio bursts (Proceedings of the Astronomical
Society of Australia) .
Preparation of a text book on plasma astrophysics was suspended
early in the year after about two thirds of the book had been written.
Preparation of the book has been recommenced .
P.J. Sands
Previous work on the analytical tools for use in the design and
analysis of optical systems incorporating inhomogeneous glasses was
continued. Papers discussing (i) the third order aberrations of media
with axial index distributions and (ii) the paraxial chromatic aberra
tions of media with either axial or cylindrical distributions were
published. Work is proceeding on a computer programme which will
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trace paraxial and non-paraxial rays through an arbitrary index dis
tribution with an axis of symmetry and compute the third order
aberrations of such a distribution. Based on data supplied by
Professor G. Horridge (Department of Neurobiology), a model of the
index distribution of an insect's eye is being constructed
preparatory to a study of the performance of the eye.
A computer programme was written for the computation of the
aberration coefficients of orders three, five, seven and nine of a
symmetric system of spherical surfaces. Checks on the programme and
the analytical formulae upon which the programme is based were devised
and applied successfully.
Formulae were derived for the computation of the aberration coef
ficients of orders one, two and three of systems which have a plane of
symmetry but are otherwise arbitrary . Two papers have been submitted
to the Journal of the Optical Society of America . A paper was written
and published discussing the first order image forming properties of
the most general optical system.
The refraction of particles at surfaces of discontinuity of the
electro-magnetic potentials was investigated and a paper has been
accepted for publication in Optik . Together with H. A. Buchdahl, a
paper discussing the question of reversibility of semi-symmetric
systems in the context of both light and particle optics has been
written. This has been accepted for publication in Optik.
Academic Staff :
Professor :
Senior Lecturer :
Lecturer :
Temporary Lecturer:
Postdoctoral Fellow:
H. A. Buchdahl, D.Sc . (Lond.), F.A. A.
D.B. Melrose, B.Sc.(Tas . ), D.Phil . (Oxon).
M. Andrews, B. Sc., M.Sc . ,(Qld.), Ph . D. (Birm.) (on study leave Jan. 1971 - Jan . 1972) .
R. T . Cahill, B. Sc., Ph . D. (N. S.W.) (vice M. Andrews on study leave) .
P. J . Sands, B.Sc., Ph . D. (A . N.U . ) .
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Publications:
Buchdahl, H.A. - Optica Acta,~ (1971), 453-459. "Hamiltonian Optics. III. The phase characteristic".
Buchdahl, H.A. -Tensor N.S . , 1£ (1971), 315-316. "Remark on the classification of tensors and tensor densities".
** Cahill, R.T. + and Sloan, I . H. -Nuclear Physics, A~ (1971), 161-179. "Theory of neutron-deuteron break-up at 14.4 Me~'.
Melrose, D.B. - Astrophysics and Space Science, lQ (1971), 186-196. "A classical derivation of inverse Compton radiation".
Melrose, D.B. - Astrophysics and Space Science, lQ (1971), 197-202. "Electrostatic bremsstrahlung".
Melrose, D.B. - Astrophysics and Space Science, lQ (1971), 458-463. Reply to comments on "On the formation of energy spectra in synchrotron sources" .
Melrose, D.B. -The Crab Nebula, I . A.U. Symposium (ed. Davies and Smith), (1971), 296-307. "Transfer of energy to the Crab nebula following the spin-up of the pulsar".
Melrose, D.B. - Astrophysical Letters,] (1971), 35-37. "Synchrotron radiation from particles with small pitch angles".
Melrose, D.B. - Astrophysics and Space Science, Jl (1971), 172-192 . "On the degree of polarization of synchrotron radiation".
Melrose, D.B . - Astrophysical Letters,] (1971), 227-229 . "Correlation between linear and circular polarization in synchrotron sources ?" .
Melrose, D. B. - Astrophysics and Space Science, (1971). "Induced Compton scattering by relativistic particles".
Melrose, D. B. and Sy, W. - Proceedings of the Astronomical Society of Australia, l (1971) . 56-57 . "Possible causes of line splitting in drift pair solar bursts".
Melrose, D.B . - Twelfth International Conference on Cosmic Rays, 1 (1971), 390-394 . "Scattering of higher energy cosmic rays".
Sands, P. J. - Journal of the Optical Society of America,~ (1971), 777-783.
... k*
:j:
"Inhomogeneous lenses . II. Chromatic paraxial aberrations .
Based on work done prior t o joining this University (a substantial amount of work and compilation having been done at this University) .
Not a member of this University.
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Sands, P.J . - Journal of the Optical Society of America,~ (1971), 879-885. "Inhomogeneous lenses. Ill. Paraxial optics" .
Sands, P. J. - Journal of the Optical Society of America,~ (1971), 1086. "Inhomogeneous lenses . IV. Aberrations of lenses with axial index distributions".
+ Sands, P. J. and Moore, D.T . - Journal of the Optical Society of America, &J (1971), 1195-1201 . "Third order aberrations of inhomogeneous lenses with cylindrical index distributions".
Sands, P.J. -Journal of the Optical Society of America, 61 (1971). "Inhomogeneous lenses . V. Chromatic paraxial aberrat'Gns of lenses with axial or cylindrical index distributions.
Sands, P.J. -Journal of the Optical Society of America, 61 (1971) . "Remarks on the first order optics of the general optical system" .
Sands, P.J. - Optica Acta,~ (1971), 627-636 . "Visual aberrations of afocal systems".
+ ** Slaus, I. et al. and Cahill, R. T. - Physical Review Letters, 1Q (1971), 789-792. "Neutron-neutron quasifree scattering" .
During the year Dr . Cahill visited Flinders University where he
gave a seminar . Dr. Melrose gave a lecture at the May meeting of the
Australian Astromonical Society, two lectures to the C. S.I .R . O.
Division of Radio Physics, and a lecture at the Twelfth International
Conference on Cosmic Rays in Hobart, all these being on astrophysical
subjects.
** Based on work done prior to joining this University (a substantial amount of work and compilation having been done at this University) .
Not a member of this University .
THE AUSTRALIAN NATIONAL UNIVERSITY
DEPARTMENT OF THEORETICAL PHYSICS ANALYSIS OF STUDENT PERFORMANCE
Subject Wastage High
Enrolled Wastage plus Sitting Distinction Credit or unit failure
Distinction
2 3 4 5 6 7 8
Theor Phys COl 10 0 10 2 3 2
Theor Phys C02 8 0 2 8 4 0
Theor Phys C03 6 0 3 6 2 0
Enrolled Sitting Results
Final Honours 3 3 1 Hl; 2 deferred
Masters Qualifying
Ordinary Degree
Masters Degree
Ph.D.
Pass with Pass Fail Merit
9 10 11
2
2
3 3
(headings above do not apply)
00
00 0 -